Fall-prevention safety device

ABSTRACT

The invention concerns a fall-prevention safety device comprising a shaped member permanently fixed along the path to be covered; a slide member displaceable along the shaped member, and a locking device comprising an eccentric cam pivoted on a portion of the slide member and provided with a coupling member. The active portion of the cam is able to be displaced between an inoperative position in which the slide member is displaced freely along the shaped member, and a locking position in which a portion of the shaped member is gripped between said cam and a portion of the slide member such that any relative displacement between the shaped member and the slide member is prevented.

I United States Patent 51 3,674,1 16 Vogeli 1 July 4, 1972 [54]FALL-PREVENTION SAFETY DEVICE 1,576,210 3/1926 Nickson ..1s2 5 1,586,2695/1926 Smith ....188/67 [72] Inventor. Rudolf Vogeli, Wettmgen,Switzerland 2,448,765 9/1948 Browning I 188/67 [73] Assignee: LebagLeitungs-Und Elektrobau AG, 3,179,994 4/1965 Meyer et al. ....l88/65.-2X Wettingen, Switzerland 3,317,971 5/1967 Meyer ..l82/5 X [22] Filed:Sept 1970 Primary Examiner-Duane A. Reger [21] Appl.No.: 76,006Att0rneyYoung&Thompson [30] Foreign Application Priority Data [57]ABSTRACT The invention concerns a fall-prevention safety device com-Oct. 9, 1969 Switzerland ..l5,l46/69 prising a shaped member permanentlyfixed along the path to be covered; a slide member displaceable alongthe shaped [52] U.S.CI "188/671 /26/51922,118888//l484 member, and alocking device comprising an eccentric Cam 51 I t Cl M 59/02 pivoted ona portion of the slide member and provided with a d 19149} couplingmember. The active portion of the cam is able to be 1 0 1883/65 44displaced between an inoperative position in which the slide 1 member isdisplaced freely along the shaped member, and a locking position inwhich a portion of the shaped member is gripped between said cam and aportion of the slide member [56] References Cited such that any relativedisplacement between the shaped UNlTED STATES PATENTS member and theslide member is prevented.

375,031 12/1887 Westbrook 182/192 6 Claims, 2 Drawing FiguresFALL-PREVENTION SAFETY DEVICE There are numerous fall-prevention safetydevices, ranging from a simple belt provided with attachment means toautomatic devices. The latter are of two different types, the one typecomprising a cable or a cord as the retaining element, which areintended more particularly for travelling work, the other typeconstituting fixed installations.

The devices having a cable or a cord suffer from the disadvantages whichare involved in periodic detailed inspection of the cable or cord and inaddition, as they are not designed as a fixed installation, it isnecessary for the cord to be secured first to the highest point, thisoperation being effected without the benefit of a safety device.

The existing fixed fall-prevention safety installations have a rigidelement which forms a kind of toothed bar disposed along the pathcovered. A slide member to which the workman is secured, is displaceablealong the toothed bar and carries a member which is actuated by the fallof the workman, to lock the slide member on the toothed bar. The maindisadvantage of this kind of device lies in the fact that the pitch ofthe toothed bar is large, of the order of 15 centimeters, so that if hefalls, the workman is subjected to a not inconsiderable shock.

The present invention concerns a fixed fall-prevention safety devicewhich is intended to overcome the above mentioned disadvantages. Thisdevice comprises a shaped member which is permanently fixed along thepath to be covered, and which is intended to receive a slide memberwhich is displaceable along the shaped member and is provided with alocking device comprising an eccentric cam pivoted on a portion of theslide member and being provided with a coupling member, the activeportion of which cam is displaced between an inoperative position inwhich the slide member is displaced freely along the shaped member, anda locking position in which a portion of the shaped member is grippedbetween said active portion of the cam and a portion of the slide membersuch that any relative displacement between the shaped member and theslide member is prevented.

The accompanying drawing illustrates diagrammatically and by way ofexample an embodiment of the fall-prevention safety device according tothe invention.

FIG. 1 shows a side elevation in partial section of a part of the shapedmember, and the slide member,

FIG. 2 is a cross-section taken along the line AA of FIG. I.

The fall-prevention safety device illustrated comprises a longitudinallyopen shaped member of which the cross-section is of the general shapefor example of a C, the shaped member being rigidly fixedly along thedistance to be covered, for example along a ladder. The shaped membercan be continuous or, as illustrated, can comprise sections 1 which areset end to end and which are held in an aligned position by sleeves 2.The shaped member can be fixed by welding, bolting, or generally by anyassembly means which enable the shaped member to be rigidly andpermanently fixed along the path to be covered.

The device also comprises a slide member having a portion 3 which isheld captive within the space inside the shaped member. The portion 3 isextended by an external portion 4 which projects out of the shapedmember by way of its longitudinal opening. In this embodiment the slidemember is T- shaped in cross-section, the internal faces of the wings ofthe T-shape sliding along the internal surface of the rim portions 5which border the opening in the shaped member.

Fixed on each side of the external portion 4 of the slide member areguide shoes 6 which, with the wings of the internal portion 3 of theslide member, form grooves to receive the rim portions 5 of the shapedmember.

The slide member 3, 4 can thus be freely displaced along the shapedmember 1, 2, without being able to escape out of the shaped member.

The slide member 3, 4 is provided with a locking device comprising aneccentric cam 7 which is pivoted on a spindle 8 passing through theexternal portion 4 of the slide member.

The eccentric cam 7 comprises two active portions 9 which are disposedon each side of the external portion 4 of the slide member, and oppositethe external surfaces of the rim portions 5 of the shaped member. Thecam 7 extends beyond its pivot spindle 8 over a certain distance, so asto form a lever arm, and is temiinated at its free end by a couplingmember, formed in this embodiment by a hole 10 which carries a ring 11to which the user can hook himself by means of a snap hook.

In the active or locking position, the active portions 9 of the cam 7are, as illustrated in the drawing, applied against the rim portions 5of the shaped member which is tightly gripped between the internalportion 3 of the slide member and the active portions 9 of the cam 7.The greater the force applied to the coupling member 10, the greater thegripping force to lock the slide member on the shaped member.

If however in normal use, the user moves the coupling member 10upwardly, that is to say, causes the cam 7 to pivot in the directionindicated by the arrow F, the active portions 9 of the earn 7 move awayfrom the rim portions 5 of the shaped member and the slide member isfree to move along the shaped member.

The locking device of the slide member also comprises a pushrod 12 whichis slidable in a bore 13 formed in the external portion 4 of the slidemember and which bears against the central portion 14 of the cam 7. Thepushrod 12 is acted upon by a spring 15 which tends to displace ittowards the cam 7. The spring 15 bears against a screw-threaded plug 16which is screwed into the upper part of the bore 13 which isscrewthreaded. A locking screw 17 is provided to fix the plug 16.

Thus, the cam is continuously subjected to the thrust of the spring 15which tends to place it in the locking position. In this manner, if theuser of the device falls, the angular amplitude of the movement of thecam 7 is reduced to a minimum, which permits immediate locking of theslide member on the shaped member.

In addition, the force of the spring 15 is calculated so asapproximately to counterbalance the weight of the slide member 3, 4.

The advantages of the fall-prevention safety device described are itssimplicity, its robustness permitting easy and straightforwardmanufacture, a minimum of maintenance or none at all, and in particularits speed of action in the case of the user falling. Tests have shownthat the locking distance, that is to say, the displacement of the slidemember with respect to the shaped member, between the moment at whichthe user loses his footing, and the moment at which he is supported bythe locking device, is of the order of one centimeter. There istherefore not sufficient time for the user to begin a free fall, and theshock to which he is subject is greatly reduced.

It is obvious that in alternative embodiments, the cross-section of theshaped member could be of a different shape; in that case, thecross-section of the slide member would be accordingly modified.

In addition, in some uses, for example for ladders for climbing onspherical tanks, it is necessary for the safety device to be able tofollow a curved path. This is readily possible, it is sufificient forthe shaped member 1 to be curved, and for suffrcient clearance to beprovided between the portion 3 of the slide member and the internalwalls of the shaped member, so that the slide member can be displaced inthe curves of the shaped member.

It should also be noted that for good operation of the fallpreventionsafety device, the portion 3 of the slide member only has to form agripping support in line with the active portions 9 of the cam 7. Thusthe length of the portion 3 of the slide member can be reduced, so thatthe slide member can move without difiiculty in the curves of the shapedmember.

In the case where the portion 3 of the slide member would be very short,it is possible to provide a second portion 3 which is separated from thefirst portion and which is located in line with the shoes 6 in order toguide the slide member.

I claim:

l. A fixed fall-prevention safety device, comprising a stationaryelongated channel member having flanges that extend toward each otherbut are spaced from each other thereby to define a gap therebetween thatextends lengthwise of said channel member, a slide member having aninternal portion disposed within said channel member and of a size toolarge to pass through said gap, said slide member having an externalportion that extends out through said gap, an eccentric cam pivotallymounted on said external portion of the slide member, said cam bearingagainst the outer side of at least one of said flanges to grip said atleast one flange between said cam and said internal portion of the slidemember thereby to permit movement of said slide member in one directionlengthwise of said channel member but to inhibit movement of said slidemember lengthwise of said channel member in the opposite direction.

2. A safety device as claimed in claim 1, and means resiliently urgingsaid cam into engagement with said at least one flange.

3. A safety device as claimed in claim 1, said cam being in the form ofa yoke that straddles said external portion of said slide member andthat bears against the outer sides of both of said flanges.

4. A safety device as claimed in claim 3, said yoke having a U-shapedportion having legs disposed on opposite sides of said external portionof the slide member, said legs bearing against said flanges, and meanspassing through said legs and through said external portion pivotally tomount said cam on said external portion.

5. A safety device as claimed in claim 1, said channel member being intwo sections disposed end to end, and a sleeve external to said sectionsand interconnecting said sections.

6. A safety device as claimed in claim 1, said channel member comprisingthe edge of a ladder.

i i :I l

1. A fixed fall-prevention safety device, comprising a stationaryelongated channel member having flanges that extend toward each otherbut are spaced from each other thereby to define a gap therebetween thatextends lengthwise of said channel member, a slide member having aninternal portion disposed within said channel member and of a size toolarge to pass through said gap, said slide member having an externalportion that extends out through said gap, an eccentric cam pivotallymounted on said external portion of the slide member, said cam bearingagainst the outer side of at least one of said flanges to grip said atleast one flange between said cam and said internal portion of the slidemember thereby to permit movement of said slide member in one directionlengthwise of said channel member but to inhibit movement of said slidemember lengthwise of said channel member in the opposite direction.
 2. Asafety device as claimed in claim 1, and means resiliently urging saidcam into engagement with said at least one flange.
 3. A safety device asclaimed in claim 1, said cam being in the form of a yoke that straddlessaid external portion of said slide member and that bears against theouter sides of both of said flanges.
 4. A safety device as claimed inclaim 3, said yoke having a U-shaped portion having legs disposed onopposite sides of said external portion of the slide member, said legsbearing against said flanges, and means passing through said legs andthrough said external portion pivotally to mount said cam on saidexternal portion.
 5. A safety device as claimed in claim 1, said channelmember being in two sections disposed end to end, and a sleeve externalto said sections and interconnecting said sections.
 6. A safety deviceas claimed in claim 1, said channel member comprising the edge of aladder.